This invention relates to data communications, and in particular to the communication of multimedia documents from multimedia servers to multimedia clients.
The Internet currently provides users with a number of different services. One of such services is the WorldWide Web, or xe2x80x9cthe Webxe2x80x9d, which has now become relatively well-known and well-used by fixed terminal subscribers.
To access the Web, a user installs a xe2x80x9cbrowserxe2x80x9d application on a terminal, which acts as a client interfacing with a network of distributed Web servers via the Internet.
In order to access a page on the Web, a user specifies a universal resource locator (URL), and transmits a pace request via a data link to the Internet. In the Internet, the request is routed to the appropriate Web server as identified in the URL. In return, the Web server transmits the pages back to the requesting browser. The communications protocol used within the Internet is TC/IP during this dialogue.
Web pages are currently formatted using the HyperText markup language (HTML). A Web browser, on receipt of a HTML document, interprets the HTML commands in order to format the text correctly. HyperText links may be included in the document which, when presented to the user, may be selected in order to request a further Web page (a HTML link references a further URL with which the browser retrieves the further page). Web pages currently contain not only text and hyperlinks, but also image, audio and/or video files (hence, Web pages are referred to as xe2x80x9cmultimediaxe2x80x9d documents).
Although the textual data in the Web page is generally relatively data-compact, it is recognized that graphics files, audio files, and in particular video files, contain relatively large amounts of data which can reduce related download of Web pages considerably. As a result, the downloading of xe2x80x9ctruexe2x80x9d multimedia documents including graphics, audio and/or video files can be cumbersome, in particular where the data link used into the Internet is of a type which is of a relatively low data rate.
The speed of download of multimedia Web pages is particularly problematic in the case of mobile data links such as a cellular radio data link, in which the radio data transfer is constrained by the relatively low bandwidth of the radio interface link.
Therefore, although it is currently possible to access the Web at a mobile communications terminal, the option is currently not widely taken advantage of and, when taking advantage of, the data transferred is generally limited to textual data to achieve reasonable download speeds.
Methods are known whereby the amount of data transfer involved in accessing the Web are reduced. In particular, many browsers support a caching facility whereby a Web page, once downloaded, is temporarily stored locally on the client terminal. When the Web page is next requested, the browser recognizes, by the URL in the request corresponding with the URL of the cached document, that the document is currently held locally, and retrieves the locally-held page in preference to re-downloading the page from the Web. The browser may transmit an update check to the Web server in question in order to confirm that the locally-stored Web page remains valid, and if not, downloads the updated Web page.
Caching may be performed on a session-by-session basis, or may be performed such that a cached Web page remains stored between sessions. However, a browser maintains only a limited non-volatile cache of Web pages, and newly-cached Web pages are stored in preference to previously-stored Web pages (which are then deleted) when the cache becomes full.
In accordance with one aspect of the present invention there is provided a multimedia client terminal, said terminal comprising:
a browser for interpreting a multimedia document received from a remote server, said interpreting means comprising:
means for recognizing textual presentation markup tags in said document and presenting text to a user in accordance with said markup tags;
means for recognizing a standard set of document-independent local library file markup tags in said document;
means for storing a set of non-textual local library files corresponding to said local library tags; and
means for presenting the contents of one of said local library files to a user in response to the recognition of one of said local library file tags in said multimedia document.
Rather than needing to download non-textual files accompanying the text of a document, the client terminal is able to receive one or more of a known set of document-independentand data-efficient markup tags and access locally-stored files which correspond to the tags in the downloaded document.
The arrangement of the present invention is to be contrasted with the arrangement in which the client terminal holds a non-volatile cache (although, such a cache may be used in combination with the present invention), in that caching mechanisms do not utilize document-independent local library markup tags. Instead, a document is cached by selection of a URL, and it is unlikely that, when a new multimedia document is downloaded, any parts of the document will already be held locally.
The use of a non-volatile cache is non-systematic, and does not allow a server content developer to design multimedia documents specifically for low data-rate communication links, which is possible with the present invention.
In addition, a non-volatile cache arrangement does not allow a user of a low data-rate receiving terminal to be confident that a new multimedia document can be downloaded at an acceptable speed, which is possible with the present invention.
By defining a standard set of document-independent local library file tags, the present invention allows a server content developer to include one or more of such tags within a document to be placed on a server in the knowledge that a user, provided with a client application for recognizing the predefined set of local library tags and for retrieving appropriate locally-stored files, will be able to download the document relatively quickly and receive each of the intended multimedia parts as intended.
The present invention is of particular utility in relation to mobile communications terminals.
Further aspects of the invention are set out in the appended claims.
Further features of embodiments of the invention are as follows:
1. The system employs tags to locally stored graphical images, drawing primitives, pre-drawn images, image manipulators, audio and video files.
2. A first set of tags provides basic two dimensional drawing functionality, enabling the creation of a range of simple but effective composite images by means ofcombinations of drawings primitives.
3. The client functionality supports a standard predefined range of pre-drawn images that can add further graphical content to a page, over and above that achieved using the drawing primitives. This enables an image to be retrieved from the local repository to be displayed at the specified co-ordinates. A scaling factor may be specified to dynamically resize the image and a hyperlirik can be optionally provided.
4. The client functionality supports the manipulation of on-screen bitmap images.
5. A second set of tags provides basic audio playback capability. The system employs tags to stored speech files as well as the ability to interpret xe2x80x9ctalking Web pagesxe2x80x9d through text to speech translation software.
6. The client functionality supports a standard predefined range of audio files enabling a file to be retrieved from the local repository, and spoken by a speech agent at the client.
7. The speech agent supports default vocal and facial styles in order to allow different genders, accents and languages into the playback. Different facial appearances may be selected for the agent. The combination of attributes may be used to create agents with different personalities.
8. A third set of tags provides basic video clip playback capability. The system employs tags to stored video files.
9. The client functionality supports a standard predefined range of video files enabling a file to be retrieved from the local repository and replayed at the client.
10. In one embodiment, tags implementing the new functionality are embedded into Web pages, which may also contain HTML, and content handlers filter out the tags implementing the new functionality before resolving them.
11. In another embodiment, references to files implementing the new functionality are embedded into Web pages, which may also contain HTML, as markups (e.g. for graphics resources  less than imgsrc=xe2x80x9cimages/text.hgmlxe2x80x9d greater than ; for audio resources  less than spesrc=xe2x80x9caudio/test.hsml greater than ; and for video resources  less than vidsrc=xe2x80x9cvideo/test.hvmlxe2x80x9d greater than ).
12. In a further embodiment, pages implementing the new functionality are a separate resource, which may be hyperlinked in the corresponding Web pages containing HTML (e.g. hnp://www.test.com/text.hgml).
13. The drawing functionality provided by tags to graphics primitives supports Web page navigation by means of hyperlinks.